Vibration instrument for bone audition



June 9, 19.25. 1,540,783

. F.- w. -KRANZ VIBRATION INsTRUMENT FoR-BQNE AUDITIO .Filed Marh 29. 1923 EEEEE drawings, and to the numerals of reference Patented June 9, 1925.

v'EEEnEEI'cK W.. xnANz, or GENEVA, ILLINoI'sf,

v'I'EEA'rIoN INSTRUMENT ron EoNE AUDITION.

Application led March 29, 1923. Serial No. 628,683.

To all wlwm tmay concern.'

Be it knownthat I, FREDERICK W. KRANZ, a citizen of the United States, and a 'resident of Geneva, .in the co-unty of Kane and State of Illinois, have invented certain new and useful Improvements in a Vibration Instrument for Bone Audition; and. I do hereby declare that the following is a full, clear, and exact description of the same,- Vreference being had to the accompanying markedthereon, which form apart of this specification.. v

yThis invention relates to means by which a person who isdeaf or partially deaf to ordinary air vibration may be made to hear by-means of vibrations conducted through his bones.

n object of the present invention is to produce an instrument for use in the investigation of the hearing through the bones .by people who are deaf to ordinary air vibration. The instrument, however, can also be used to investigate bone audition in Vcases where the air audition is normal.

It is a further object of :this invention to provide an instrument ofthe sort indicated which will-itself produce very little vibration in the air, so that it is' available for ,investigations of the sort just .mentioned and also for investigations of the hearing of lower animals, vfish and the like.

It is a further object of the invention to providean instrument by which alternating electric current either of va constantperiod or of the characterof theusual telephone currents may be translated into mechanical vibration which can be transmitted to the bones ofthe subject. A

' It is av further object of this invention to provide an instrument of the A'kind indicated which shall produce vibrations of 'v small amplitude but large force.

' It is a further object of `the invention to provide an instrument 'of the sort indicated Whose efficiency will not be materially dithe personuot` the subject.

Other and further important objects of this invention will be apparent` from the disclosures in the specification and the laccompanying drawings.

minishedbv pressing the instrument against Figure 1 is a top plan view of one form of my invention. -s l v v Figure 2 is a side view, partially `in ksection, of the same. l.

Figure- 3 is a sect-ion upon the line .3-3 of Figure 2.

Figure 4 is a central section of` another form of the invention. l Figure 5 is an end view of the form shown in Fig. 4. f

As shown on the drawings; The linstrument, includes an iron core 10 having a central Inemberll and pole pices 12 which are turned 'in toward said` central member,.so as to leave a small'airgap. The

m-:issfuru fPATEN'I (OFFICE.

central member .-11 carries a winding 13 d which is sup-plied with `direct current in any f .piece is of any elastic non-magnetic material such as brass or hard rubber or the like. It is spaced away from the magnetic frame 10 by spacer blocks 15 of nonfmag- I1.9 and 20. The center ofthe fspool is. holl netic material. In the center of its under low in order to surround the upper end of the middle member 11 of the magnetic frame 10'. As illustrated, the upper end of the hollow in the spool-is closed to make a solid-floor for connection with the bar 14 It will, however, be obvious that any method for connecting `the spool to the bar may be used.

From the upper surfaceof the bar 1A in the center, that is, opposite the imddle ofthe spool 16, goes a nod 21 which supports a disk 22, preferably of hardrubber inorthat the pressure is transmitted to the mastoid bone, the vibration produced by the -der that it may be pressed against the person ofthe .subject under investigation without discomfort. The leads of the' winding 18. arev provided with a flexible portion 23 in order lthat these leads shallnot interfere with 'the motion ofthe winding 18.

In the form of the device illustrated in Figures 4 and 5, a permanent magnet 30 has its pole pieces surrounded by windings 31. These windings and the permanent magnet are enclosed within a hard rubber casing 32 and the leads from the windings 31 are 'broughtout of the small end of this casing vas-shown at 33; all of this structure being, closely similar to that of the usual telephone Y receiver. Instead-of a diaphragm, as in the riods may be adjusted in the usual way by l lusual telephone receiver, a` bar 34 of magnetic material is placed across the vopen end of the casing 32 in close proximityfto the pole pieces of the magnet 30. Thisbar is made of a thickness considerably greater than that of a'telephone diaphragm, in order that when the instrument is pressed.

against-the hearer, the distance from the bar y34 to the pole pieces 31 shall be altered only slightly. The bar is firmly secured in place in any desired manner; for example, it may be. fastened by screws 35 to-a ring 36 and the rin screw-threaded onto the casing 32. From t ecenter ofthe bar 34 rises a rod 21 similar to the rod 2 1 in the other form of device and 'ending in `a disk 22 of suitable material sim` ar to the disk 22 already described'.

In. Ithe use of the form of vthe device shown in Fi ures` 1 to 3, alternating current is introduce through the leads 23 into the winding 18.l This current may be of a fixed period such as would beobtained from a vacuum tubel oscillator used in connection with an amplifier if desired. The ixed pe variable condensers or inductances. The alternatin current introduced into the leads 23 may, i desired, come from the receiving is desired to investigate,may be used, no`

set of a wireless telephone outfit. Or, if de# sired, it may be a lcurrent from the receiving instrument of an ordinary wire form of telephone. Any other form of alternating current', which corresponds to `sounds that it matter w at sort ofapparatus is needed to' produce t 's alternating current. The alternating current flowing in the coils 18 in the midst of the ma etic field produced by the coil -14 or by t e permanent magnet will cause strong impulses to be given, first in one direction and then in the other to the wires'18 and so to the spool 16. There will thus be exerted a thrust first up and then down against the bar 14 which will be transl 'mitted through the rod 21 to the disk 22.

Ifthis disk is pressed against thehead of the person whose' hearing 1s being studied so 'the combined action of said ma thrusts just described will be transmitted ,to the mastoid bone and so through the'bones of the head to the internal ear. The instrument may, however, be pressed against the hearers person at any other point wheie the bony structure comes near enough to the surface to give a firm support for the pressure. For example, vit may be applied to the shin bone or to bonesvof the head' other than the mastoid bone, or to the teeth. The result is that vibrations are communicated to the bones of the hearer and so to his ears. Because of the narrow shape of the bar 14, the vibrating system in the instrument has but little surface in contact with the air.

Very little vibration in the air itself will therefore be set up. For this reason, when the instrument is used in connection with a telephone receiving device and a microphone such as are frequently used in outfits for entheoutiit to sing or howl will be much less than with such outfits as heretofore made.

' In the form illustrated in Figures 4 and 5, the operation is very similar.n Instead, however, of the magnetic fieldl producing a thrust first in one direction and then in the other upon a coil, the alternating current in- 'troduced through ythe leads 23 to the windperson of the hearer, the bar 34 will beI slightlyl deflected toward the pole pieces of the magnet 40, but the bar is made of suffi'- cient thickness so that this deflection is not large enough to change the e'iciency of the instrument. vThis rigidity of the vibrating member allows the airgap between itand the magnetic pole pieces to be made small, with a consequent gain in the amount off force exerted on the vibrating member.

I am aware that numerous details of construction may be varied through a wide range without departing vfrom the principles of-this invention, and I thereore do not purpose limiting the patent granted otherwise thanvnecessitated y the prior art.

I claim as my invention:

1. In an apparatusior translating alter-v nating currents into mechanical vibrations, means for producing a magnetic field, la bar, means for causing vibration of said bar by etic field abling deaf people to'hear, the tendency of and said alternatingl currents, t e area of t caused by said vibrations of the bar, a disk,

and a rod connecting said disk to saidy bar. 2. In a device of the class` described, a magnetic circuit having an air gap, means for producing a constant flux through Said circuit, -a winding located `in said alr gap', ineans for producing an alternating current in said winding, means for transmitting the mechanical vibrations set up by the interaction between said alternating. current and 10 said iiux, said transmitting means including and a rod eonnecti4 a bar across the axis of said windin a disk,

said disk to said bar..

yIn` testimony w ereofl- I have hereunto subscribed my name in the presence of two subscribing witnesses.

FREDERICK KRANZ.

OSCAR Han'rmniv'. 

